Process for manufacturing a durable oily stain resistant polyester fiber,and its product

ABSTRACT

A POLYESTER FIBER ONTO WHICH A LOWER-HYDROXYALKYL METHACRYLATE WAS GRAFT-POLYMERIZED SHOWS EXCELLENT RESISTANCE TO OIL STAINING. THE NUMBER OF CARBON ATOMS OF SAID HYDROXYALKYL GROUP IS FROM ONE TO FOUR AND 2-HYDROXYETHYL METHACRYLATE IS PREFERABLY EMPLOYED.

United States Patent Int. Cl. B44a 5/12 US. Cl. 117-118 3 Claims ABSTRACT OF THE DISCLOSURE v A polyester fiber onto which 'a lower-hydroxyalkyl methacrylate was graft-polymerized shows excellent resistance to oil staining. The number of carbon atoms of said hydroxyalkyl group is from one to four and 2-hydroxyethyl methacrylate is preferably employed.

BACKGROUND OF THE INVENTION A polyester fiber is superior in mechanical and thermmal properties. The heat-set property thereof is especially useful for wash and wear goods. However, polyester fiber has some disadvantages. It has low hydroscopicity, is difficult to dye, and is easily stained by oil stains and, since it is hydrophobic, it is diflicult to remove oil stains. Especially oily soil is ditlicult to remove from polyester fiber. The oily stain permeates the fiber and makes it grey. There is another serious problem in that soil, oily or water-soluble, which is deposited onto a. textile is transferred to a polyester textile when they are washed together in a washing machine.

To make polyester fibers resistant to oil staining, and easy to remove the following methods have been proposed and are known:

(i) Treat the polyester fiber with a colloidal silica, a basic aluminium salt or an alkyl titanate. The defect of this method is that the efliect produced by the treatment is not wash-resistant and after several launderings disappears,

(ii) Treat the polyester fiber with a fiorine compound.

This method achieves resistance to oil staining; however, it has the defect that it is difiicult to remove soil deposited on the treated fiber. Furthermore, the cost of treating by this process is rather high.

(iii) Treat the polyester textile, a polyester blended yarn fabric or a polyester blend woven fabric with a condensation product of aminoaldehyde and an acrylic emulsion comprising at least 20% of acrylic acid. This method gives long-lasting oil-stain release property but the processing is rather complicated and it is expensive. The present invention achieves the desired results without the above-mentioned defects.

SUMMARY OF THE INVENTION I This invention relates to a novel stain-resistant polyester fiber and a novel process for making a polyester fiber stain resistant. Particularly, it relates to providing a polyester fiber with a durable oily stain release property by graft-polymerizing a lower-hydroxyalkyl methacrylate onto a polyester fiber or a polyester blended textile.

The term a polyester fiber in this invention means (1) poly (ethylene terephthalate) fiber, or a copolymeric polyester fiber comprising ethylene terephthalate component and another monomer or monomers such as ethylene diisophthalate component; (2) a polyester blended fiber such as blended yarn fabrics and union fabrics compris- P CC ing a polyester fiber as defined in the above (1) and other fiber materials such as a cellulose, a polyamide, a polyacrylonitrile, a polyolefin etc.; and any type of fibers such as filament, yarn, fabric or clothing.

The present invention is carried out by graft-polymerizing a lower-hydroxyalkyl methacrylate onto a polyester fiber in an amount of 05-15%, preferably 110% by weight of the fiber. The lower-hydroxyalkyl methacrylate to be used is a hydroxyalkyl methacrylate having 1 to 4 carbon atoms as the alkyl group, and 2-hydroxyet'hyl methacrylate is preferably employed.

The object of the present invention is to provide a novel stain-resistant polyester fiber and a novel process for imparting oily stain release property to a polyester fiber. Incidentally, a polyester fiber according to the present invention has the merit of being dyeable with a basic dyestuff.

Another merit of the present invention is the lower cost of the processing apparatus. The apparatus employs ordinary materials since a lower-hydroxyalkyl methacrylate is neutral, whereas acid-resistant materials must be employed in the prior art apparatus because an acidic agent such as acrylic acid etc. is used.

The oily stain release property is imparted by decreasing the oleophilic property of a polyester fiber by way of graft-polymerizing a lower-hydroxyalkyl methacrylate thereon. In other words, in the present invention the affinity between a polyester fiber and an oily stain is lowered by introducing a hydroxyl group in the form of a hydroxyalkyl methacrylate onto a polyester fiber.

The stain-resistance achieved by the present invention is superior to that brought about by graft-polymerizing acrylic acid. This is surprising since acrylic acid provides a polyester fiber with higher hydroscopicity than a lowerhydroxyalkyl methacrylate when both receive the same percentage of graft-polymerization.

The method and conditions of the graft-polymerization in the practice of the present invention can be optionally selected by one skilled in the art. As a graft-polymerization initiator, a persulfate such as ammonium persulfate can be employed when aqueous solution of the acrylate monomer is used in the polymerization, and a radical initiator such as benzoyl peroxide can be employed when the acrylate monomer or a mixture of the monomer and an organic solvent is used. The graft-polymerization can be eflectedby means of an ionizing radiation or a high energy light such as ultraviolet light. It has been found that the polymerization can also be carried out only by heating the polymerization system at a temperature between 80-150 C. without employing either an initiator or an ionizing radiation. Furthermore, the graft-polymerization can advantageously be effected by combining any of the above-mentioned means.

The useful radiations includes alpha rays, beta rays, gamma rays, electron beam, X-rays, neutrons and combinations thereof. An ultraviolet light from a mercury lamp etc. can also be utilized. The dose and dose rate of the ionizing radiation range just enough to initiate graft-polymerization to just below the amount at which the polyester fiber deteriorates. Generally the dose and dose rate are in the range of 10 -10 roentgen and 10 -10 roentgen/ hr.

Some of the modes of graft-polymerization are shown below:

(i) Process of immersing a polyester fiber in an aqueous solution of a lower-hydroxyalkyl methacrylate and carrying out polymerization at a temperature between solution thereof, squeezing the fiber so that it is impregnated with a suitable amount of the monomer and then carrying out polymerization at a temperature between 80150 C. or by means of an ionizing radiation at 50-150 C. This method is useful in that the formation of homopolymer is eifectively prevented.

In the above processes, when the temperature is higher than 150 C., the fiber deteriorates and homopolymer forms; when the temperature is lower than 80 C. and neither an initiator nor a radiation is employed, polymerization does not take place or takes place slowly.

After the graft-polymerization, the treated polyester fiber is washed well with boiling water and then with methanol at 50 C. to remove homopolymer of a lowerhydroxyalkyl methacrylate, and is dried. The term graft percent means the percent of weight increase based on the untreated fiber. A graft percent of 110% is generally enough to provide adequate stain resistance.

The main effects according to the present invention are that fats, mineral or vegetable oils, fatty acids etc. or a mixture thereof with dusts and mud, which were deposited on the treated polyester fibers, can easily be removed by an ordinary washing, and the treated polyester fiber is not stained by any oily stain dispersed in the washing solution. 1

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now the invention is illustrated by way of working examples. These examples are shown for better understanding of the invention and should not be taken as limiting the scope of the invention. The amounts shown in the examples are on the basis of weight.

Example 1 A swatch of taffeta prepared from poly (ethylene terephthalate) (yarn size, 75 denier both in warp and weft; count, warp 80 and weft 125) was scoured by means of an ordinary process. Said scouring process comprises treating the taffeta for 30 minutes in the scouring bath at 40 C. in which aqueous solution of non-ionic surfactant Neoplex P powder in 2 g./l. was put in the proportion of 30 times by weight as much as the fabric to be treated; further treating it for 30 minutes in the bath at 80 C.; washing it with hot water and then with cold water; and drying.

About 0.5 g. of the scoured sample (8 cm. x 10 cm.) was immersed in a 20% aqueous solution of 2-hydroxyethyl methacrylate at room temperature for 20' minutes and taken out, and the sample was squeezed by a mangle so that the amount of impregnant was about 50% by weight of the fabric. The squeezed sample was put in a test tube 2 cm. in diameter, and nitrogen was passed the tube for 2 minutes to replace air, followed by irradiation with gamma rays from Co-60 at the dose rate of 1.3 x10 roentgen/hr. at 100 C.

After the irradiation, the sample was washed with boiling water for 2 hours and then with methanol at 50 C. for 16 hours so as to remove unreacted monomer and homopolymer adhering to the fiber, and was dried at a reduced pressure at 50 C. The graft percent was determined by measuring the weight increases against the sample before graft polymerization. The stain release properties of the treated samples are shown in Table 1.

TABLE 1 Irradiation time Stain Min- Dose Graft, release Sample number utes Hours (roentgen) percent grade 2.5 0. 4 X 10 1. 2 4. 1.3 X 10 3. 9 4. 5 2. 6 X 10 6. 5 4. 5 3.9 X 10 12.2 4.5

Not treated.

The stain release grade was determined by (a) putting a drop of used mobile oil on the fabric, (b) washing the stained fabric with an aqueous solution of non-ionic surfactant (Neoplex P powder) in 3 g./l. concentration for 10 minutes at 60 C., and (c) measuring the degree of oil removed by means of the standard photographic plates for evaluation supplied by DMRC (Deering Milliken Research Corporation, U.S.A.). In the evaluation, grade 5 indicates the state that the oil is completely removed and grade 1 indicates that no oil is removed. The states between grades 1 and 5 are classified into 9 grades at intervals of 0.5.

The data in Table 1 shows that the polyester fabrics onto which 2-hydroxyethyl methacrylate was graftpolymerized in 1.2-12.2% indicate grade 4.0 or grade 4.5 and the oil is almost completely removed. In contrast, the grade of untreated fabric is 2.5.

The durability of stain proofing eifect by washing is evaluated in the following experiment. The treated fabric of sample No. 3 was washed with aqueous solution of Neoplex P Powder in 3 g./1. concentration for 200 minutes at 60 C. with vigorous stirring. These conditions of washing correspond to washing 20-30 times by means of an ordinary domestic washing machine. After the washing, the sample indicates grade 4.5 in the stain proofing test. This proves that the stain proofing treatment according to the present invention is sufficiently wash-resistant.

Example 2 Example 1 was repeated except for using 10% aqueous solution of 2-hydroxyethyl methacrylate and irradiating the impregnated sample with electron beam from Van de Graaif accelerator of 1.5 m.e.v. and 100 ya. at C. in air. The irradiation was eifected by passing the sample once at the speed of 18 cm./min. under the window of the accelerator. The average dose rate was 0.5 Mrad/ sec. and the absorbed dose was 3.6 Mrad.

After the irradiation, the unreacted monomer and homopolymer were removed and the graft percent was measured as in Example 1. The graft percent and stain release grade were 2.4% and 4.5 respectively.

Example 3 A swatch of poly (ethylene terephthalate) taffeta which had been scoured as in Example 1 was immersed in a 10% aqueous solution of 2-hydroxyethyl methacrylate and kept at C. for 1 hour in nitrogen atmosphere. After that, the unreacted monomer and homopolymer were removed, and the weight increase was measured. The graft ratio and stain resistant grade of the treated fabric were 4.5% and 3.5 respectively.

Example 4 Broadcloth consisting of poly (ethylene terephthalate) and cotton, the blending ratio being 65:35, yarn size being 75 denier both in warp and weft, and count being 142 in warp and 72 in weft, was treated with the conventional processes in order to carry out desizing, scouring, bleaching and heat set.

Then, the sample was immersed in 10% aqueous solution of 2-hydroxyethyl methacrylate at room temperature for 10 minutes and taken out, and squeezed by a mangle so that the amount of impregnant was about 50% by weight of the fabric. The squeezed sample was put in a test tube 2 cm. in diameter, and nitrogen was passed thereto for 2 minutes to replace air therein, followed by irradiation with gamma rays from Co-60 sources at the dose rate of 1.3 10 roentgen/hr. for 30 minutes at 100 C. After the irradiation, the unreacted monomer and homopolymer were removed as in Example 1. The graft percent and stain release grade were 3.0% and grade 3.5 respectively.

In contrast, the stain release grade of the untreated broadcloth is grade 1.5. This comparison proves that the present invention is very effective also on blended fibers.

What is claimed is:

1. .A durable oily stain resistant fiber onto which 2- hydroxyethyl methacrylate is graft polymerized in an amount of 0.5-15% by weight of the fiber, said fiber being'selected from the group consisting of (i) apoly (ethylene terephthalate) fiber,

(ii) a copolymeric polyester fiber comprising ethylene terephthalate as a component,

(iii) a blended fiber comprising said fiber (i) as a major component, and

(iv) a blended fiber comprising said fiber (ii) as a major component.

2. The stain-resistant fiber of claim 1 in which the amount of graft polymerization is l-l0% by weight of said fiber.

3. A stain-resistant fiber as set forth in claim 1, in which said polyester fiber is a poly (ethylene terephthalate) fiber or a copolymeric polyester fiber comprising ethylene terephthalate as a component.

References Cited UNITED STATES PATENTS T. G. aDAVIS, Assistant Examiner US. Cl. X.R. 

